DOI Page / Citation link:
https://doi.org/10.11588/diglit.62828#0080
( 3° )
This fcale may likewife be ufed in laying down any angle*
not more than ninety degrees. Draw the line G oy Fig. 16, at
plealure; then take the chord 6o° and fweep the arch o o at plea-
lure. With your compalTes take the chord 37°! and place it on
the arch 0 0; draw the right line G 0, and you have an angle of
thirty-feven degrees and an half, and fo of any other, to ninety
degrees.
On the Protractors.
The Protractor is a femicircle of brafs, divided into one
hundred and eighty degrees, by the help of which we may de-
fcribe an angle of any affigned quantity whatever, and likewife
meafure any angle already laid down.
Let the arch, divided into one hundred and eighty equal
parts, on the line A B, Fig. 6, Plate I. be conlidered as the
brafs protraClor, which is found in common cafes of inftru-
ments.
* Angle. “ This feems to be from AvxvAo?, ankulos, the bending of the elbowand in
Geometry, implies the point in which two lines meet: but the quantity of an angle is the
fpace comprehended between the two lines meeting in a point, as o o, Plate IL Fig. 16, and
its proportion is exprelied by degrees; which term, Degree, means limply the three hundred
and fiftieth part of a circle, whether great or fmall.
t Protractor, from protrafium, “ to draw out in length accordingly, by the help of
this inftrument we may draw out the legs of a triangle to any length we pleafe.
Firft,
This fcale may likewife be ufed in laying down any angle*
not more than ninety degrees. Draw the line G oy Fig. 16, at
plealure; then take the chord 6o° and fweep the arch o o at plea-
lure. With your compalTes take the chord 37°! and place it on
the arch 0 0; draw the right line G 0, and you have an angle of
thirty-feven degrees and an half, and fo of any other, to ninety
degrees.
On the Protractors.
The Protractor is a femicircle of brafs, divided into one
hundred and eighty degrees, by the help of which we may de-
fcribe an angle of any affigned quantity whatever, and likewife
meafure any angle already laid down.
Let the arch, divided into one hundred and eighty equal
parts, on the line A B, Fig. 6, Plate I. be conlidered as the
brafs protraClor, which is found in common cafes of inftru-
ments.
* Angle. “ This feems to be from AvxvAo?, ankulos, the bending of the elbowand in
Geometry, implies the point in which two lines meet: but the quantity of an angle is the
fpace comprehended between the two lines meeting in a point, as o o, Plate IL Fig. 16, and
its proportion is exprelied by degrees; which term, Degree, means limply the three hundred
and fiftieth part of a circle, whether great or fmall.
t Protractor, from protrafium, “ to draw out in length accordingly, by the help of
this inftrument we may draw out the legs of a triangle to any length we pleafe.
Firft,